ok, im sure i am basically answering all my own questions here, and i just KNOW im gonna catch **** for it. but i just put in an exhaust cutout just before the resonator on my ss/sc.
im on stock sc stock injectors and stock pulley...from 3500+ rpm it works great. but on startup it lopes until it dies...throws codes like a bitch...and bottom end is fucked...is this just a tuning issue or just not enough back pressure on stock components?

 

I have 3 inch piping all the way back to the stock muffler with the cutout just after the rear wheels and mine runs fine, but I also have a tune. But it started and ran fine even before tunning. My bottom ends not as good when it's open but it's not that much worse. Maybe you put it to far upstream in the exhaust and possibly not a good tune